JP2009231801A - Organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having high light emission efficiency, low driving voltages and excellent durability. <P>SOLUTION: The organic electroluminescent element having at least one organic compound layer containing a light emission layer interposed between a pair of electrodes includes a layer containing a compound represented by general formula (1) inside the light emission layer and in at least one area of the light emission layer facing the adjacent layer of the light emission layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescent element (hereinafter sometimes referred to as an organic EL element) that can be effectively used for a surface light source such as a full color display, a backlight, and an illumination light source, and a light source array such as a printer.

  The organic EL element is composed of a light emitting layer or a plurality of organic layers including a light emitting layer and a counter electrode sandwiching the organic layer. In the organic EL element, electrons injected from the cathode and holes injected from the anode are recombined in the organic layer, emitted light from the generated excitons, and other molecules generated by energy transfer from the excitons. It is an element for obtaining light emission using at least one of light emission from the excitons.

  Until now, organic EL elements have been developed with greatly improved brightness and element efficiency by using a laminated structure with separated functions. For example, a two-layer stacked device in which a hole transport layer and a light-emitting / electron transport layer are stacked, a three-layer stacked device in which a hole transport layer, a light-emitting layer, and an electron transport layer are stacked, a hole transport layer, and a light-emitting layer A four-layer stacked element in which a hole blocking layer and an electron transport layer are stacked is often used.

  However, many problems still remain for practical use of organic EL elements, such as improving luminous efficiency and driving durability. In particular, increasing the light emission efficiency can reduce power consumption and is also advantageous in terms of driving durability, and thus many improvement means have been disclosed so far.

  For example, an organic EL device is disclosed in which an electrically inactive material is added to a layer adjacent to the light emitting layer to prevent diffusion of excitons generated in the light emitting layer to the adjacent layer and to block charge (for example, Patent Documents 1 and 2). However, an increase in driving voltage due to an increase in electrical resistance is inevitable.

On the other hand, a search for a light-emitting material that is thermally and chemically stable and has high light emission efficiency is also in progress. For example, an adamantane derivative having excellent thermal and chemical stability by using a compound having a rigid adamantane structure in the molecule is used as a light emitting material of the light emitting layer, or an adamantane derivative is used as the light emitting material of the light emitting layer. Furthermore, an organic EL element containing an adamantane derivative in an adjacent layer is disclosed (for example, see Patent Document 3). However, the adamantane derivative has a problem of poor charge transportability, low luminous efficiency, and high driving voltage. In addition, an organic EL device containing an adamantane compound having an unsubstituted or linear or branched alkyl group as a substituent in the light emitting layer as a host compound and a guest compound is expected to improve luminous efficiency and driving durability. Is disclosed (for example, see Patent Document 4). However, since the adamantane compound does not have a charge transport property, the charge flows only on the guest compound. Accordingly, the driving voltage increases due to the inclusion of the adamantane compound, and a great improvement in luminous efficiency cannot be expected. Further, it is disclosed that an organic EL device having particularly high heat resistance and high luminous efficiency can be provided by using an adamantane compound having an ortho-terphenyl group as a host material of a light emitting layer (for example, Patent Documents). 5). However, in order for organic EL elements to be put into practical use, in addition to high light emission efficiency and high drive durability, it is possible to operate at a low drive voltage, to enable light emission in a wide light emission wavelength region, etc. Many characteristics to be provided are required. In the structure of the light emitting layer disclosed in Patent Document 5, it cannot be said that these requirements can be sufficiently met.
JP 2005-294248 A JP 2005-294249 A JP 2003-321402 A JP 2006-120811 A Japanese Patent Laid-Open No. 2005-220080

  An object of the present invention is to provide an organic EL device having high luminous efficiency, low driving voltage, and excellent durability.

The present invention has been made in view of the above problems, and is achieved by the following means.
<1> An organic electroluminescent device having at least one organic compound layer including a light emitting layer sandwiched between a pair of electrodes, the region of the light emitting layer facing the inside of the light emitting layer and the adjacent layer of the light emitting layer An organic electroluminescent device comprising a layer containing a compound represented by the following general formula (1) on at least one of the following:

(In General Formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or aryl. Group, heteroaryl group, alkoxy group having 1 to 6 carbon atoms, acyl group, acyloxy group, amino group, nitro group, cyano group, ester group, amide group, halogen atom, perfluoroalkyl group having 1 to 6 carbon atoms, Represents a silyl group, and at least one of R _{1 to} R ₄ is a group having a double bond or a triple bond, X _{1 to} X ₁₂ each independently represents a hydrogen atom, an alkyl having 1 to 6 carbon atoms; Group, alkenyl group having 2 to 6 carbon atoms, alkynyl group having 2 to 6 carbon atoms, aryl group, heteroaryl group, alkoxy group having 1 to 6 carbon atoms, acyl group, acyloxy group, amino group, nitro group, cyano group , D Ether group, an amide group, a halogen atom, a perfluoroalkyl group having 1 to 6 carbon atoms, a silyl group.).
<2> The organic electroluminescence device according to <1>, wherein the layer containing the compound represented by the general formula (1) has a thickness of 0.1 nm or more and less than 3 nm.
<3> The organic electroluminescent element according to <1> or <2>, wherein the layer containing the compound represented by the general formula (1) is an intermediate thin layer inside the light emitting layer.
<4> Any one of <1> to <3>, wherein the layer containing the compound represented by the general formula (1) is an interfacial thin layer facing the anode of the light emitting layer. The organic electroluminescent element as described.
<5> Any one of <1> to <4>, wherein the layer containing the compound represented by the general formula (1) is an interface thin layer facing the cathode of the light emitting layer. The organic electroluminescent element as described.
<6> A plurality of the intermediate thin layers are provided inside the light emitting layer, and the plurality of intermediate thin layers are arranged at intervals of 5 nm or more and 20 nm or less. <3> to <5> The organic electroluminescent element in any one.
<7> The energy difference (denoted as Eg) between the highest occupied orbital and the lowest unoccupied orbital of the compound represented by the general formula (1) is 4.0 eV or more <1> to <6 > The organic electroluminescent element in any one of>.
<8> in either of the triplet lowest excitation level of the compound represented by the general formula (1) _{(T 1} hereinafter) is characterized in that at least 2.7 eV <1> ~ <7> The organic electroluminescent element as described.
<9> The organic electroluminescence according to any one of <1> to <8>, wherein the compound represented by the general formula (1) has an electron affinity (denoted as Ea) of 2.3 eV or more. element.
<10> The organic electroluminescence according to any one of <1> to <9>, wherein an ionization potential (denoted as Ip) of the compound represented by the general formula (1) is 6.1 eV or more. element.
<11> The organic electroluminescent element according to any one of <1> to <10>, wherein the group having a double bond is an aryl group.
<12> The organic electroluminescent element according to <11>, wherein the aryl group is a phenyl group.
<13> The organic electroluminescent element according to any one of <1> to <12>, wherein the light emitting layer contains a metal complex.
<14> The organic electroluminescence device according to <13>, wherein the metal complex is a metal complex having a tridentate or higher ligand.
<15> The organic electroluminescent element according to <13> or <14>, wherein the metal complex is a metal complex represented by the following general formula (A):

(In General Formula (A), M ¹¹ represents a metal ion, and L ^{11 to} L ¹⁵ each independently represents a ligand coordinated to M ^{11. An} atomic group between L ¹¹ and L ¹⁴ May be further present to form a cyclic ligand, L ¹⁵ may be bonded to both L ¹¹ and L ¹⁴ to form a cyclic ligand, and Y ¹¹ , Y ¹² and Y ¹³ are Each independently represents a linking group, a single bond, or a double bond, and when Y ¹¹ , Y ¹² , or Y ¹³ is a linking group, L ¹¹ and Y ¹² , Y ¹² and L ¹² , L ¹² And Y ¹¹ , Y ¹¹ and L ¹³ , L ¹³ and Y ¹³ , and Y ¹³ and L ¹⁴ each independently represent a single bond or a double bond, and n ¹¹ represents 0 to 4. M binding of ¹¹ and ^L 11 ^{~L 15} are each independently, coordinate bond, an ionic bond, Izu covalent bond But good.).
<16> The organic electroluminescent device as claimed in <15>, wherein the ^{M 11} in Formula (A) is a platinum ion.

  ADVANTAGE OF THE INVENTION According to this invention, it has high luminous efficiency, a low drive voltage, and the organic EL element excellent in durability is provided.

Hereinafter, the organic electroluminescent element of the present invention (hereinafter sometimes referred to as “organic EL element” as appropriate) will be described in detail.
The light-emitting device of the present invention is an organic electroluminescent device having a cathode and an anode on a substrate and sandwiching at least one organic compound layer including a light-emitting layer between the electrodes. It has a layer containing the compound represented by General formula (1) in at least one of the area | region of the said light emitting layer which faces the adjacent layer of a layer.
The layer containing the compound represented by the general formula (1) in the present invention is preferably a compound in which 50% by mass or more of the layer is represented by the general formula (1), more preferably. 80% by mass or more, more preferably 90% by mass or more, and most preferably 100% by mass is the compound represented by the general formula (1).

  In the present invention, the layer containing the compound represented by the general formula (1) is preferably a thin layer having a thickness of 0.1 nm or more and less than 3 nm. More preferably, they are 0.1 nm or more and 2 nm or less, More preferably, they are 0.5 nm or more and 2 nm or less. When the thickness of the layer containing the compound represented by the general formula (1) is 3 nm or more, the driving voltage is increased and the light emission efficiency is decreased, which is not preferable. Moreover, when the film thickness is less than 0.1 nm, the effect of the layer in the present invention cannot be exhibited, which is not preferable.

Preferably, the layer containing the compound represented by the general formula (1) is an intermediate thin layer inside the light emitting layer. More preferably, a plurality of the intermediate thin layers are provided inside the light emitting layer, and the plurality of intermediate thin layers are arranged at intervals of 5 nm or more and 20 nm or less.
Preferably, the layer containing the compound represented by the general formula (1) is an interface thin layer on the side facing the anode of the light emitting layer, or an interface thin layer on the side facing the cathode of the light emitting layer. is there. More preferably, a layer containing the compound represented by the general formula (1) is provided inside the light emitting layer, on the side facing the anode of the light emitting layer, and on the side facing the cathode of the light emitting layer.

  In view of the properties of the light emitting element, at least one of the anode and the cathode is preferably transparent.

  The organic compound layer in the present invention may be either a single layer or a laminate. As an aspect in the case of lamination, from the anode side, a charge transport layer that transports positive charges (hereinafter sometimes referred to as a hole transport layer), a light emitting layer, a charge transport layer that transports negative charges (hereinafter referred to as a positive charge transport layer) , And may be described as an electron transport layer). Further, a charge blocking layer or the like may be provided between the hole transport layer and the light-emitting layer, or between the light-emitting layer and the electron transport layer. A hole injection layer may be provided between the anode and the hole transport layer, and an electron injection layer may be provided between the cathode and the electron transport layer. Each layer may be divided into a plurality of secondary layers.

The configuration of the light emitting layer in the present invention will be described in more detail with reference to the drawings. The drawing shows only the hole transport layer and the electron transport layer adjacent to the light emitting layer related to the configuration of the present invention, and other organic layers, electrodes, and the like are omitted from the drawing.
FIG. 1 shows a conventional configuration in which a hole transport layer 4, a light emitting layer 1, and an electron transport layer 3 are laminated in this order from the anode side. In the conventional configuration in which no special countermeasure is taken, a part of excitons generated in the light emitting layer diffuses into the adjacent hole transport layer and electron transport layer, and quenches and disappears, resulting in a decrease in light emission efficiency. A phenomenon occurs. In addition, excitons are mainly generated in the interface region between the hole transport layer and the electron transport layer of the light emitting layer, and the central portion of the layer does not contribute to light emission effectively, which is inefficient.

FIG. 2 is an example of an embodiment according to the present invention, and is an ultrathin interfacial thin layer 2a, 2b containing a compound represented by the general formula (1) in the interface region facing the anode side and the cathode side of the light emitting layer. Have According to this configuration, the inefficiency is improved because diffusion of excitons generated in the light emitting layer to the adjacent hole transport layer and electron transport layer is prevented.
In addition, the interface thin layer in this invention means the layer laminated | stacked on the anode side interface or cathode side interface of a light emitting layer with the thin film thickness of 0.1 nm-less than 3 nm.

FIG. 3 shows another example of an embodiment according to the present invention characterized by having ultrathin intermediate thin layers 12 and 14 containing only the compound represented by the general formula (1) inside the light emitting layer 10. According to this configuration, excitons are generated in the light emitting layer along the entire light emitting layer, and the excitons generated inside the light emission are effectively held inside, so that the light emission efficiency is improved.
The intermediate thin layer in the present invention is a thin layer having a thickness of 0.1 nm to less than 3 nm and is inserted into the light emitting layer.

  FIG. 4 shows the most preferred embodiment according to the present invention, and the interface thin layers 20a and 20b containing only the compound represented by the general formula (1) in the interface region facing the anode side and the cathode side of the light emitting layer 100. The light emitting layer 100 includes intermediate thin layers 120 and 140 containing only the compound represented by the general formula (1). According to this configuration, excitons are generated in the light emitting layer along the entire light emitting layer, excitons generated inside the light emission are effectively held inside, and excitons generated in the light emitting layer are generated. Since diffusion to the adjacent hole transport layer and electron transport layer is prevented, extremely high luminous efficiency can be achieved. In addition, none of the interface thin layers 2a0 and 20b and the intermediate thin layers 120 and 140 in the present invention emit light.

  In the present invention, the number of the intermediate thin layers disposed inside the light emitting layer is not particularly limited, but is preferably about 1 to 30, more preferably 1 to 20, and still more preferably 2 from the viewpoint of ease of production. -10.

1. Description of the compound represented by the general formula (1) Next, the compound represented by the general formula (1) used in the organic electroluminescence device of the present invention will be described in detail.

(In General Formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or aryl. Group, heteroaryl group, alkoxy group having 1 to 6 carbon atoms, acyl group, acyloxy group, amino group, nitro group, cyano group, ester group, amide group, halogen atom, perfluoroalkyl group having 1 to 6 carbon atoms, Represents a silyl group, and at least one of the R _{1 to} R ₄ is a group having a double bond or a triple bond, X _{1 to} X ₁₂ are each independently a hydrogen atom or a group having 1 to 6 carbon atoms; Alkyl group, alkenyl group having 2 to 6 carbon atoms, alkynyl group having 2 to 6 carbon atoms, aryl group, heteroaryl group, alkoxy group having 1 to 6 carbon atoms, acyl group, acyloxy group, amino group, nitro group, cyano Group, Ester group, an amide group, a halogen atom, a perfluoroalkyl group having 1 to 6 carbon atoms, a silyl group.).

Examples of the alkyl group having 1 to 6 carbon atoms represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl (that is, 2 -Butyl), isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.

Examples of the alkenyl group having 2 to 6 carbon atoms represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include vinyl, allyl (that is, 1- (2-propenyl)), 1- (1- Propenyl), 2-propenyl, 1- (1-butenyl), 1- (2-butenyl), 1- (3-butenyl), 1- (1,3-butadienyl), 2- (2-butenyl), 1 -(1-pentenyl), 5- (cyclopentadienyl), 1- (1-cyclohexenyl) and the like.

Examples of the alkynyl group having 2 to 6 carbon atoms represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include ethynyl, propargyl (that is, 1- (2-propynyl)), 1- (1- Propynyl), 1-butadiynyl, 1- (1,3-pentadiynyl) and the like.

Examples of the aryl group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include phenyl, o-tolyl (that is, 1- (2-methylphenyl)), m-tolyl, p-tolyl, 1- (2,3-dimethylphenyl), 1- (3,4-dimethylphenyl), 2- (1,3-dimethylphenyl), 1- (3,5-dimethylphenyl), 1- (2,5 -Dimethylphenyl), p-cumenyl, mesityl, 1-naphthyl, 2-naphthyl, 1-anthranyl, 2-anthranyl, 9-anthranyl, and 4-biphenylyl (ie, 1- (4-phenyl) phenyl), 3 -Biphenylyls such as biphenylyl, 2-biphenylyl, 4-p-terphenylyl (i.e. 1-4- (4-biphenylyl) phenyl), 4-m-terphenylyl (i.e. Terphenylyls such as 1-4- (3-biphenylyl) phenyl).

Examples of the heteroaryl group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include a nitrogen atom, an oxygen atom, a sulfur atom, and the like as the hetero atom contained therein. Specifically, Examples include imidazolyl, pyrazolyl, pyridyl, pyrazyl, pyrimidyl, triazinyl, quinolyl, isoquinolinyl, pyrrolyl, indolyl, furyl, thienyl, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl, azepinyl and the like.

Examples of the alkoxy group having 1 to 6 carbon atoms represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include methoxy, ethoxy, isopropoxy, cyclopropoxy, n-butoxy, tert-butoxy, cyclohexyloxy , Phenoxy and the like.

Examples of the acyl group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include acetyl, benzoyl, formyl, and pivaloyl.

Examples of the acyloxy group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include acetoxy, benzoyloxy, and the like.

Examples of the amino group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, pyrrolidino, piperidino, morpholino and the like. Can be mentioned.

Examples of the ester group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include methyl ester (that is, methoxycarbonyl), ethyl ester, isopropyl ester, phenyl ester, benzyl ester, and the like.

Examples of the amide group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include N, N-dimethylamide (that is, dimethylaminocarbonyl) and N-phenylamide linked by a carbon atom of the amide. N, N-diphenylamide, N-methylacetamide (that is, acetylmethylamino), N-phenylacetamide, N-phenylbenzamide and the like linked by a nitrogen atom of the amide.

Examples of the halogen atom represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the perfluoroalkyl group having 1 to 6 carbon atoms represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include trifluoromethyl, pentafluoroethyl, 1-perfluoropropyl, and 2-perfluoro. Examples include propyl and perfluoropentyl.

Examples of the silyl group having 1 to 18 carbon atoms represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ include trimethylsilyl, triethylsilyl, triisopropylsilyl, triphenylsilyl, methyldiphenylsilyl, dimethylphenylsilyl. , Tert-butyldimethylsilyl, tert-butyldiphenylsilyl, and the like.

Said R < ₁ > -R < ₄ > and X < ₁ > -X < ₁₂ > may be further substituted by another substituent. For example, examples of the alkyl group substituted with an aryl group include benzyl, 9-fluorenyl, 1- (2-phenylethyl), 1- (4-phenyl) cyclohexyl, etc., and the aryl group substituted with a heteroaryl group Examples thereof include 1- (4-N-carbazolyl) phenyl, 1- (3,5-di (N-carbazolyl)) phenyl, 1- (4- (2-pyridyl) phenyl) and the like.

R _{1 to} R ₄ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an amino group, an ester group, or a silyl group, and more preferably a hydrogen atom. , An alkyl group, an aryl group, a heteroaryl group, an alkoxy group, an amino group, and a silyl group, and particularly preferably a hydrogen atom, an alkyl group, and an aryl group.

X _{1 to} X ₁₂ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an amino group, an ester group, or a silyl group, and more preferably a hydrogen atom. , An alkyl group and an aryl group, particularly preferably a hydrogen atom.

The alkyl group having 1 to 6 carbon atoms represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ is preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclopentyl, and cyclohexyl are more preferable, and methyl, ethyl, tert-butyl, n-hexyl, and cyclohexyl are more preferable, and methyl and ethyl are particularly preferable.

The aryl group represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ is preferably phenyl, o-tolyl, 1- (3,4-dimethylphenyl), 1- (3,5-dimethylphenyl). , 1-naphthyl, 2-naphthyl, 9-anthranyl, and biphenylyls and terphenylyls, more preferably phenyl, biphenylyls, and terphenylyls, and more preferably phenyl.

The hydrogen atom represented by R _{1 to} R ₄ and X _{1 to} X ₁₂ may be a deuterium atom, and is preferably a deuterium atom.

  Part or all of the hydrogen atoms contained in the compound represented by the general formula (1) may be substituted with deuterium atoms.

At least one of R _{1 to} R ₄ is a double bond or a group having a triple bond. Examples of the double bond include C═C, C═O, C═S, C═N, N = N, S = O, P = O, etc., preferably C = C, C = O, C = N, S = O, P = O, more preferably C = C, C = O, C = N, particularly preferably C = C. Examples of the triple bond include C≡C and C≡N, and preferably C≡C.

As the group having a double bond or triple bond of R _{1 to} R ₄ , an aryl group is preferable, and among them, a phenyl group, a biphenylyl group, and a terphenylyl group represented by the following are preferable, and a phenyl group is particularly preferable.

At least one of R _{1 to} R ₄ is a group having a double bond or a triple bond, but the number of R _{1 to} R ₄ having a double bond or a triple bond is preferably 2 to 4, 3 -4 is more preferable, and 4 is particularly preferable.

When the number of R _{1 to} R ₄ having a double bond or triple bond is 1 to 3, R ^{1 to} R ⁴ consisting of only the remaining single bond is a hydrogen atom, an alkyl group, an alkoxy group, or a silyl group. Preferably, a hydrogen atom, an alkyl group, and a silyl group are preferable, and a hydrogen atom and an alkyl group are particularly preferable.

R _{1 to} R ₄ and X _{1 to} X ₁₂ may be linked to each other to form a ring structure. For example, as described below, X ₂ , X ₃ , and X ₉ may be linked to each other to form a diamantane structure, and X ₄ , X ₅ , and X ₁₂ are linked to each other to form a triamantane structure. May be formed. These diamantane structure and triamantane structure may be further substituted with a substituent.

  In the present invention, the compound represented by the general formula (1) is preferably mixed and contained. Preferably, compounds having different groups having a double bond, or compounds having different numbers of substitution can be used in combination. Examples of the group having a double bond include the above phenyl group, biphenylyl group, and terphenylyl group, and examples thereof include compounds having 1 to 4 substitutions. For example, a mono-substituted product having a substitution number of 1 and a tetra-substitution product having a substitution number of 4 can be used.

In the present invention, when a plurality of compounds represented by the general formula (1) are mixed and used, the mixing ratio is preferably in the range of 1:99 to 99: 1 by mass ratio for one compound. More preferably, it is in the range of 20:80 to 80:20.
By using a mixture of a plurality of compounds represented by the general formula (1), further improvement in luminous efficiency and improvement in driving durability can be achieved.

  Specific examples of the compound represented by the general formula (1) used in the present invention are given below, but the compound of the present invention is not limited to these.

In the present invention, the energy difference (expressed as Eg) between the highest occupied orbit and the lowest unoccupied orbit of the compound represented by the general formula (1) is preferably 4.0 eV or more.
The compound represented by the general formula (1) in the present invention performs the action of suppressing the diffusion of excitons and blocking holes or electrons (preventing cylinder omission). Since the energy difference Eg between the highest occupied orbit of the electrically inactive organic compound and the lowest unoccupied orbit is 4.0 eV or more, the above effect can be exhibited. Eg is more preferably 4.1 eV or more, and particularly preferably 4.2 eV or more.

  The triplet lowest excitation level T1 of the electrically inactive organic compound is preferably 2.7 eV or more. This is preferable in that the exciton diffusion from the light emitting material of the light emitting layer is suppressed and the light emission efficiency can be further improved. When the light-emitting material is a phosphorescent blue light-emitting material, its T1 is about 2.6 eV, and in order to suppress triplet exciton diffusion from now on, T1 of an electrically inactive organic compound is more than that, that is, 2. It is preferable that it is 7 eV or more, and by doing so, the luminous efficiency can be further improved in the phosphorescent blue light emitting device.

  Furthermore, in the present invention, the ionization potential Ip of the electrically inactive organic compound is preferably 6.1 eV or more. This is preferable in that the movement of holes from the light emitting material of the light emitting layer to the electrically inactive organic compound is suppressed, and the light emission efficiency can be further improved. Further, Ip is more preferably 6.2 eV or more, and particularly preferably 6.3 eV or more. In particular, when the light emitting material is a phosphorescent blue light emitting material, its ionization potential is 5.8 to 5.9 eV, and in order not to move holes from this phosphorescent blue light emitting material to an electrically inactive organic compound, The ionization potential of the electrically inactive organic compound is preferably more than that, that is, 6.0 eV or more. By doing so, the luminous efficiency can be further improved in the phosphorescent blue light-emitting device. In particular, in the case of using a phosphorescent material, the ionization potential of N, N′-dicarbazolyl-1,3-benzene (abbreviated as mCP) used as a host material in the light-emitting layer is 5.9 eV. In order to suppress the hole clogging of holes to the cathode side adjacent layer, it is preferably larger than that value, and by setting it to 6.1 eV or more, hole clogging of holes can be suppressed and the luminous efficiency is further improved. can do.

  The electron affinity of the electrically inactive organic compound is preferably 2.3 eV or less. In this case, it is preferable from the viewpoint that emission of electrons from the light emitting layer (mainly, removal of electrons from the host material of the light emitting layer) is suppressed, and the luminous efficiency can be further improved. The electron affinity of N, N′-dicarbazolyl-1,3-benzene (abbreviated as mCP) used as a host material in the light emitting layer is 2.4 eV, and electrons are removed from the mCP to the adjacent layer on the anode side of the light emitting layer. In order to suppress this, it is preferably smaller than that value, and by setting it to 2.3 eV or less, it is possible to suppress the omission of the electron tube and to further improve the light emission efficiency.

2. Light-emitting layer The light-emitting layer receives holes from the anode, hole injection layer, or hole transport layer when an electric field is applied, receives electrons from the cathode, electron injection layer, or electron transport layer, and recombines holes and electrons. It is a layer having a function of providing light and emitting light.
The light emitting layer in the present invention preferably contains at least one kind of electron transport material and at least one kind of hole transport material, and at least one of the electron transport material and the hole transport material is a light emitting material.
As the electron transporting material, an electron transporting light emitting material or an electron transporting host material is used. As the hole transporting material, a hole transporting light emitting material or a hole transporting host material is used.

  Although the thickness of the light emitting layer in this invention is not specifically limited, Usually, they are 1 nm-500 nm, Preferably they are 5 nm-200 nm, More preferably, they are 10 nm-100 nm.

2-1. Luminescent Material As the luminescent material, a fluorescent luminescent material and a phosphorescent luminescent material are known.

(I) Phosphorescent material As a phosphorescent material, generally, a metal complex containing a transition metal atom or a lanthanoid atom can be mentioned.
The transition metal atom is preferably ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, and platinum, more preferably rhenium, iridium, and platinum, and more preferably iridium, platinum. .
Examples of the lanthanoid atom include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.

Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Examples include ligands described in Yersin's "Photochemistry and Photophysics of Coordination Compounds" published by Springer-Verlag 1987, Akio Yamamoto "Organic Metal Chemistry-Fundamentals and Applications-" .
Specific ligands are preferably halogen ligands (preferably chlorine ligands), aromatic carbocyclic ligands (eg, cyclopentadienyl anion, benzene anion, or naphthyl anion), Nitrogen-containing heterocyclic ligands (eg, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, or phenanthroline), diketone ligands (eg, acetylacetone), carboxylic acid ligands (eg, acetate ligand) , Alcoholate ligands (eg, phenolate ligands), carbon monoxide ligands, isonitrile ligands, and cyano ligands, more preferably nitrogen-containing heterocyclic ligands.
The metal complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  Among these, specific examples of the light emitting material include, for example, US6303238B1, US6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1, WO02 / 02714A2, WO02 / 15645A1, WO02 / 44189A1, JP-A No. 2001-247859, JP-A No. 2002-302671, JP-A No. 2002-117978, JP-A No. 2002-225352, JP-A No. 2002-235076, JP-A No. 2003-123982, JP-A No. 2002-170684, EP No. 12122657, JP-A No. 2002-226495 JP, 2002-234894, JP, 2001-247859, JP, 2001-298470, JP, 2002-173673, JP, 2002-20. 678, JP 2002-203679, JP 2004-357791, and the like phosphorescent compounds described in patent documents such as JP-2006-256999.

(B) Fluorescent luminescent materials Fluorescent luminescent dopants generally include benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, pyran, perinone, oxa Diazole, aldazine, pyralidine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compounds, condensed polycyclic aromatic compounds (anthracene, phenanthroline, pyrene, perylene, Rubrene, pentacene, etc.), 8-quinolinol metal complexes, pyromethene complexes and various metal complexes represented by rare earth complexes, polythiophene, polyphenylene, poly Examples thereof include polymer compounds such as rephenylene vinylene, organic silanes, and derivatives thereof.

The light emitting material used in the present invention is preferably a phosphorescent light emitting material having an electron affinity (Ea) of 2.5 eV to 3.5 eV and an ionization potential (Ip) of 5.7 eV to 7.0 eV. The following electron transporting phosphorescent materials are used.
Specifically, ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, platinum, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium complex More preferred is a ruthenium, rhodium, palladium, or platinum complex, and most preferred is a platinum complex.

  As the phosphorescent material used in the present invention, a metal complex having a tridentate or higher ligand is particularly preferable.

(Multidentate metal complex)
The metal complex having a tridentate or higher ligand in the present invention will be described.
1) Metal ion The atom coordinated to the metal ion in the metal complex is not particularly limited, but is preferably an oxygen atom, a nitrogen atom, a carbon atom, a sulfur atom or a phosphorus atom, more preferably an oxygen atom, a nitrogen atom or a carbon atom, More preferred are nitrogen or carbon atoms.

  The metal ion in the metal complex is not particularly limited, but is preferably a transition metal ion or a rare earth metal ion from the viewpoint of improving luminous efficiency, improving durability, and lowering driving voltage, iridium ion, platinum ion, gold ion, Rhenium ion, tungsten ion, rhodium ion, ruthenium ion, osmium ion, palladium ion, silver ion, copper ion, cobalt ion, zinc ion, nickel ion, lead ion, aluminum ion, gallium ion, or rare earth metal ion (for example, europium) An iridium ion, a platinum ion, a gold ion, a rhenium ion, a tungsten ion, a palladium ion, a zinc ion, an aluminum ion, a gallium ion, and the like. , Europium, cadmium, or terbium, more preferably iridium, platinum, rhenium, tungsten, europium, cadmium, or terbium, and more preferably iridium. Platinum ion, palladium ion, zinc ion, aluminum ion, or gallium ion, and most preferably platinum ion.

2) Coordination number The metal complex having a tridentate or higher ligand in the present invention is preferably a metal complex having a tridentate or higher and a hexadentate or lower ligand from the viewpoint of improving luminous efficiency and durability. In the case of a metal ion that easily forms a hexacoordinate complex represented by iridium ion, a metal complex having a tridentate, tetradentate, or hexadentate ligand is more preferable, and platinum ion is representative. In the case of a metal ion that easily forms a tetracoordinate complex, a metal complex having a tridentate or tetradentate ligand is more preferable, and a metal complex having a tetradentate ligand is more preferable.

3) Ligand From the viewpoint of improving luminous efficiency and durability, the ligand of the metal complex in the present invention is preferably a chain or a ring, and a central metal (for example, a general formula (A) described later) In the case of a compound represented by the formula, N ¹¹ represents a nitrogen-containing heterocycle coordinated with nitrogen (for example, pyridine ring, quinoline ring, pyrimidine ring, pyrazine ring, pyrrole ring, imidazole ring, pyrazole ring). Oxazole ring, thiazole ring, oxadiazole ring, thiadiazole ring, or triazole ring). The nitrogen-containing heterocycle is more preferably a nitrogen-containing 6-membered heterocycle or a nitrogen-containing 5-membered heterocycle. These heterocycles may form condensed rings with other rings.

  That the ligand of the metal complex is a chain means that the ligand of the metal complex does not have a cyclic structure (for example, a terpyridyl ligand). Further, that the ligand of the metal complex is cyclic means that a plurality of ligands in the metal complex are bonded to each other to form a closed structure (for example, phthalocyanine ligand, crown ether coordination). Etc.).

4) Preferred Metal Complex Structure The metal complex in the present invention is preferably an organic compound represented by the general formula (A) described in detail below.

<Metal complex represented by general formula (A)>
First, the organic compound represented by the general formula (A) will be described.

In the general formula (A), M ¹¹ represents a metal ion, and L ^{11 to} L ¹⁵ each represents a ligand coordinated to M ¹¹ . An atomic group may further exist between L ¹¹ and L ¹⁴ to form a cyclic ligand. L ¹⁵ may combine with both L ¹¹ and L ¹⁴ to form a cyclic ligand.
Y ¹¹ , Y ¹² and Y ¹³ each represent a linking group, a single bond or a double bond. When Y ¹¹ , Y ¹² , or Y ¹³ is a linking group, L ¹¹ and Y ¹² , Y ¹² and L ¹² , L ¹² and Y ¹¹ , Y ¹¹ and L ¹³ , L ¹³ and Y ¹³ , Y ¹³ And the bond between L ¹⁴ each independently represents a single bond or a double bond. n ¹¹ represents the 0-4. The bond between M ¹¹ and L ^{11 to} L ¹⁵ may be any of a coordination bond, an ionic bond, and a covalent bond.

The organic compound represented by the general formula (A) will be described in detail.
In the general formula ^{(A), M 11} represents a metal ion. Although it does not specifically limit as a metal ion, A bivalent or trivalent metal ion is preferable. As the divalent or trivalent metal ion, platinum ion, iridium ion, rhenium ion, palladium ion, rhodium ion, ruthenium ion, copper ion, europium ion, gadolinium ion, terbium ion are preferable, platinum ion, iridium ion, or Europium ions are more preferred, platinum ions and iridium ions are more preferred, and platinum ions are particularly preferred.

In general formula (A), L ¹¹ , L ¹² , L ¹³ , and L ¹⁴ each independently represent a ligand that coordinates to M ¹¹ . The atoms contained in L ¹¹ , L ¹² , L ¹³ , and L ¹⁴ and coordinated to M ¹¹ are preferably a nitrogen atom, an oxygen atom, a sulfur atom, a carbon atom, or a phosphorus atom. An atom, a sulfur atom, or a carbon atom is more preferable, and a nitrogen atom, an oxygen atom, or a carbon atom is still more preferable.

The bonds formed by M ¹¹ and L ¹¹ , L ¹² , L ¹³ , and L ¹⁴ may each independently be a covalent bond, an ionic bond, or a coordinate bond. For convenience of explanation, the ligand in the present invention shall be used not only in the case of a coordination bond but also in the case of being formed by other ionic bonds or covalent bonds.
The ligand consisting of L ¹¹ , Y ¹² , L ¹² , Y ¹¹ , L ¹³ , Y ¹³ , and L ¹⁴ is an anionic ligand (a ligand in which at least one anion binds to a metal). Is preferred. 1-3 are preferable, as for the number of anions in an anionic ligand, 1 and 2 are more preferable, and 2 is further more preferable.

L ¹¹ , L ¹² , L ¹³ , and L ¹⁴ coordinated to M ¹¹ by a carbon atom are not particularly limited, but are each independently an imino ligand, an aromatic carbocyclic ligand (for example, a benzene ligand). , Naphthalene, anthracene, or phenanthracene ligands), heterocyclic ligands (eg, thiophene ligands, pyridine ligands, pyrazine ligands, pyrimidine ligands, thiazole ligands) Ligands, oxazole ligands, pyrrole ligands, imidazole ligands, pyrazole ligands, and condensed rings containing them (eg, quinoline ligands, benzothiazole ligands, etc.) and their tautomers Sex body).

L ¹¹ , L ¹² , L ¹³ , and L ¹⁴ coordinated to M ¹¹ by a nitrogen atom are not particularly limited, but each independently includes a nitrogen-containing heterocyclic ligand (eg, pyridine ligand, pyrazine coordination). Ligand, pyrimidine ligand, pyridazine ligand, triazine ligand, thiazole ligand, oxazole ligand, pyrrole ligand, imidazole ligand, pyrazole ligand, triazole ligand, oxadi Azole ligands, thiadiazole ligands, and condensed rings containing them (for example, quinoline ligands, benzoxazole ligands, benzimidazole ligands, etc.) and tautomers thereof (note that In the present invention, in addition to the usual isomers, the following examples are also defined as tautomers, for example, the 5-membered heterocyclic ligand of the compound (24) described later and the 5-membered terminal of the compound (64). Arocyclic ligands, 5-membered heterocyclic ligands of the compound (145) are also defined as pyrrole tautomers, etc.) amino ligands (alkylamino ligands (preferably having 2 to 30 carbon atoms, More preferably, it has 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include methylamino.), Arylamino ligands (for example, phenylamino), acylamino ligands (Preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino), alkoxycarbonylamino ligands (preferably Has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonylamino. ), An aryloxycarbonylamino ligand (preferably having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, and examples thereof include phenyloxycarbonylamino). Sulfonylamino ligands (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino, benzenesulfonylamino, etc.), imino. These ligands may be further substituted.

L ¹¹ , L ¹² , L ¹³ , and L ¹⁴ coordinated to M ¹¹ with an oxygen atom are not particularly limited, but are independently an alkoxy ligand (preferably having 1 to 30 carbon atoms, more preferably having carbon atoms). 1 to 20, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy), aryloxy ligands (preferably 6 to 30 carbon atoms, more preferably Has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy, 1-naphthyloxy, 2-naphthyloxy and the like, and a heterocyclic oxy ligand (preferably having 1 carbon atom). To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridyloxy, pyrazyloxy, pyrimidyloxy, Noryloxy, etc.), acyloxy ligands (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetoxy, benzoyloxy and the like. ), A silyloxy ligand (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include trimethylsilyloxy and triphenylsilyloxy). , Carbonyl ligands (eg, ketone ligands, ester ligands, amide ligands, etc.), ether ligands (eg, dialkyl ether ligands, diaryl ether ligands, furyl ligands, etc.) Can be mentioned.

Although it does not specifically limit as L < ¹¹ >, L < ¹² >, L <^13> , and L < ¹⁴ > coordinated to M < ¹¹ > by a sulfur atom, Each is independently alkylthio ligand (preferably C1-C30, More preferably, carbon number. 1 to 20, particularly preferably 1 to 12 carbon atoms, for example, methylthio, ethylthio, etc.), an arylthio ligand (preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably Has 6 to 12 carbon atoms, for example, phenylthio and the like, and a heterocyclic thio ligand (preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms). And examples thereof include pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio), and thiocarbo. Le ligands (e.g. thioketone ligand, etc. thioester ligands), or thioether ligands (e.g. dialkyl thioether ligands, diaryl thioether ligands, etc. thiofuryl ligand), and the like. These substituted ligands may be further substituted.

L ¹¹ , L ¹² , L ¹³ , and L ¹⁴ coordinated to M ¹¹ with a phosphorus atom are not particularly limited, but each independently includes a dialkylphosphino group, a diarylphosphino group, a trialkylphosphine, a triarylphosphine, And a phosphinin group. These groups may be further substituted.

L ¹¹ and L ¹⁴ are each independently an aromatic carbocyclic ligand, alkyloxy ligand, aryloxy ligand, ether ligand, alkylthio ligand, arylthio ligand, alkylamino coordination Ligand, arylamino ligand, acylamino ligand, nitrogen-containing heterocyclic ligand (eg pyridine ligand, pyrazine ligand, pyrimidine ligand, pyridazine ligand, triazine ligand, thiazole ligand) Ligands, oxazole ligands, pyrrole ligands, imidazole ligands, pyrazole ligands, triazole ligands, oxadiazole ligands, thiadiazole ligands, or condensed ligand bodies containing them (For example, a quinoline ligand, a benzoxazole ligand, a benzimidazole ligand, or the like, or a tautomer thereof) is preferable, and an aromatic carbocyclic ligand Aryloxy ligands, arylthio ligands, arylamino ligands, and pyridine ligands, pyrazine ligands, imidazole ligands, or condensed ligand bodies containing them (for example, quinoline ligands) , A quinoxaline ligand, a benzimidazole ligand, or the like, or a tautomer thereof, an aromatic carbocyclic ligand, an aryloxy ligand, an arylthio ligand, or an arylamino coordination A child is further preferred, and an aromatic carbocyclic ligand or an aryloxy ligand is particularly preferred.

L ¹² and ^{L 13} each ^{independently} ligands preferably form a coordinate bond with ^{M 11,} as ligands forming a coordination bond with ^{M 11,} a pyridine ring, a pyrazine ring, a pyrimidine ring, Triazine ring, thiazole ring, oxazole ring, pyrrole ring, triazole ring, and condensed ring containing them (for example, quinoline ring, benzoxazole ring, benzimidazole ring, or indolenine ring) and their tautomerism Pyridine ring, pyrazine ring, pyrimidine ring, pyrrole ring, and condensed ring containing them (for example, quinoline ring, benzpyrrole, etc.) and tautomers thereof are more preferable, pyridine ring, More preferred are a pyrazine ring, a pyrimidine ring, and a condensed ring containing them (for example, a quinoline ring, etc.), a pyridine ring, and A condensed ring containing a pyridine ring (for example, a quinoline ring) is particularly preferable.

In the general formula (A), L ¹⁵ represents a ligand coordinated to M ¹¹ . L ¹⁵ is preferably a 1-4-dentate ligand, more preferably a 1-4-dentate anionic ligand. Although it does not specifically limit as an anionic ligand of 1-4 tetradentate, The monoanionic property containing a halogen ligand, a 1, 3- diketone ligand (for example, acetylacetone ligand etc.), and a pyridine ligand Bidentate ligand (eg, picolinic acid ligand, 2- (2-hydroxyphenyl) -pyridine ligand, etc.), L ¹¹ , Y ¹² , L ¹² , Y ¹¹ , L ¹³ , Y ¹³ , L ¹⁴ And a monoanionic bidentate ligand containing a 1,3-diketone ligand (for example, an acetylacetone ligand) or a pyridine ligand (for example, a picolinic acid ligand). A tetradentate ligand formed by L ¹¹ , Y ¹² , L ¹² , Y ¹¹ , L ¹³ , Y ¹³ , L ¹⁴ , and the like. Preferably, 1,3-diketone Ligands (eg, acetylacetone ligand), monoanionic bidentate ligands containing pyridine ligand (eg, picolinic acid ligand, 2- (2-hydroxyphenyl) -pyridine ligand, etc.) Are more preferable, and a 1,3-diketone ligand (for example, an acetylacetone ligand) is particularly preferable. The number of coordination sites and the number of ligands do not exceed the coordination number of the metal. However, L ¹⁵ does not combine with both L ¹¹ and L ¹⁴ to form a cyclic ligand.

In General Formula (A), Y ¹¹ , Y ¹² , and Y ¹³ each independently represent a linking group, a single bond, or a double bond. Although it does not specifically limit as a coupling group, For example, the coupling group comprised including the atom selected from a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a silicon atom, and a phosphorus atom is preferable. Specific examples of such a linking group include the following.

When Y ¹¹ , Y ¹² , or Y ¹³ is a linking group, L ¹¹ and Y ¹² , Y ¹² and L ¹² , L ¹² and Y ¹¹ , Y ¹¹ and L ¹³ , L ¹³ and Y ¹³ , Y ¹³ And the bond between L ¹⁴ each independently represents a single bond or a double bond.

Y ¹¹ , Y ¹² , and Y ¹³ are each independently preferably a single bond, a double bond, a carbonyl linking group, an alkylene linking group, or an alkenylene group. Y ¹¹ is more preferably a single bond or an alkylene group, and still more preferably an alkylene group. Y ¹² and Y ¹³ are more preferably a single bond or an alkenylene group, and even more preferably a single bond.

Ring formed by Y ¹² , L ¹¹ , L ¹² , and M ¹¹ , Ring formed by Y ¹¹ , L ¹² , L ¹³ , and M ¹¹ , Formed by Y ¹³ , L ¹³ , L ¹⁴ , and M ¹¹ The ring to be formed preferably has 4 to 10 ring members, more preferably 5 to 7 ring members, and further preferably 5 or 6 ring members.

In the general formula ^{(A), n 11} represents 0 to 4. If M ¹¹ is a metal coordination number ^{4, n 11} is ^0, when ^{M 11} is a metal coordination number ^{6, n 11} is 1, 2 is preferable, and more preferably 1. When M ¹¹ is coordination number 6 and n ¹¹ is 1, L ¹⁵ represents a bidentate ligand, and when M ¹¹ is coordination number 6 and n ¹¹ is 2, L ¹⁵ represents a monodentate ligand. When M ¹¹ is a metal having a coordination number of 8, n ¹¹ is preferably 1 to 4, more preferably 1, 2, and more preferably 1. When M ¹¹ is coordination number 8 and n ¹¹ is 1, L ¹⁵ represents a tetradentate ligand, and when M ¹¹ is coordination number 8 and n ¹¹ is 2, L ¹⁵ represents a bidentate ligand. When n ¹¹ is plural, a plurality of L ¹⁵ may be different even in the same.

Specific examples of the complex represented by formula (A) in the present invention are illustrated below, but the present invention is not limited thereto.

(Hole-transporting light-emitting material)
As the hole transporting light emitting material used in the present invention, a hole transporting fluorescent light emitting material or a hole transporting phosphorescent light emitting material can be used, and a hole transporting phosphorescent light emitting material is preferable.

The hole transporting luminescent material in the present invention will be described.
The hole transporting light emitting material used for the light emitting layer of the present invention preferably has an ionization potential (Ip) of 5.1 eV or more and 6.4 eV or less from the viewpoint of improving durability and lowering driving voltage. It is more preferably 4 eV or more and 6.2 eV or less, and further preferably 5.6 eV or more and 6.0 eV or less. Further, from the viewpoint of improving durability and lowering driving voltage, the electron affinity (Ea) is preferably 1.2 eV or more and 3.1 eV or less, more preferably 1.4 eV or more and 3.0 eV or less. More preferably, it is 8 eV or more and 2.8 eV or less.

Specific examples of such hole transporting light emitting materials include, for example, pyrrole compounds, indole compounds, carbazole compounds, imidazole compounds, polyarylalkane compounds, arylamine compounds, styryl compounds, In addition to styrylamine compounds, thiophene compounds, aromatic polycyclic condensation compounds, metal complexes, and the like can be given.
The metal ion in the metal complex is not particularly limited, but is preferably a transition metal ion or a rare earth metal ion, more preferably an iridium ion or platinum, from the viewpoints of improving luminous efficiency, durability, and driving voltage. Ion, gold ion, rhenium ion, tungsten ion, rhodium ion, ruthenium ion, osmium ion, palladium ion, silver ion, copper ion, cobalt ion, nickel ion, lead ion, rare earth metal ion (for example, europium ion, gadolinium ion, Terbium ions, etc.) are preferred, more preferably iridium ions, platinum ions, gold ions, rhenium ions, tungsten ions, europium ions, cadolinium ions, terbium ions, and particularly preferably iridium ions. Platinum ion, a rhenium ion, europium ion, gadolinium ion, terbium ion, most preferably iridium ion. Among metal complexes having iridium ions, particularly preferred are metal complexes having a carbon-Ir bond and a nitrogen-Ir bond (in this case, the bond may be a coordination bond, an ionic bond or a covalent bond). is there.

  Specific examples of such hole-transporting light-emitting materials include, but are not limited to, the following materials.

2-2. Host material As the host material, both a hole transporting host material and an electron transporting host material can be used.

(Electron transporting host material)
The electron transporting host material used in the present invention preferably has an electron affinity Ea of 2.5 eV or more and 3.5 eV or less, from the viewpoint of improving durability and lowering driving voltage, and 2.6 eV or more and 3.4 eV or less. It is more preferable that it is 2.8 eV or more and 3.3 eV or less. Further, from the viewpoint of improving durability and reducing driving voltage, the ionization potential Ip is preferably 5.7 eV or more and 7.5 eV or less, more preferably 5.8 eV or more and 7.0 eV or less, and 5.9 eV or more. More preferably, it is 6.5 eV or less.

  Specific examples of such an electron transporting host include pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazol, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiol. Pyrandoxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, fluorine-substituted aromatic compounds, aromatic tetracarboxylic anhydrides such as naphthalene and perylene, phthalocyanines, and their derivatives (form condensed rings with other rings) And metal complexes of 8-quinolinol derivatives, metal phthalocyanines, metal complexes having benzoxazole or benzothiazol as ligands, and the like.

Preferred examples of the electron transporting host include metal complexes, azole derivatives (benzimidazole derivatives, imidazopyridine derivatives, etc.), and azine derivatives (pyridine derivatives, pyrimidine derivatives, triazine derivatives, etc.). To metal complex compounds are preferred. The metal complex compound is more preferably a metal complex having a ligand having at least one nitrogen atom, oxygen atom or sulfur atom coordinated to the metal.
The metal ion in the metal complex is not particularly limited, but is preferably beryllium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, tin ion, platinum ion, or palladium ion, more preferably beryllium ion, Aluminum ion, gallium ion, zinc ion, platinum ion or palladium ion, and more preferably aluminum ion, zinc ion, platinum ion or palladium ion.

  There are various known ligands contained in the metal complex. For example, “Photochemistry and Photophysics of Coordination Compounds”, Springer-Verlag, H.C. Examples include the ligands described in Yersin, published in 1987, “Organometallic Chemistry: Fundamentals and Applications”, Sakai Hanafusa, Yamamoto Akio, published in 1982, and the like.

The ligand is preferably a nitrogen-containing heterocyclic ligand (preferably having 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 3 to 15 carbon atoms, and a monodentate ligand. Alternatively, it may be a bidentate or higher ligand, preferably a bidentate or higher and a hexadentate or lower ligand, or a bidentate or higher and lower 6 or lower ligand and a monodentate mixed ligand. preferable.
Examples of the ligand include an azine ligand (for example, pyridine ligand, bipyridyl ligand, terpyridine ligand, etc.), a hydroxyphenylazole ligand (for example, hydroxyphenylbenzimidazole coordination). And a hydroxyphenyl benzoxazole ligand, a hydroxyphenyl imidazole ligand, a hydroxyphenylimidazopyridine ligand, etc.), an alkoxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 carbon atom). To 20, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy), aryloxy ligands (preferably 6 to 30 carbon atoms, more preferably 6-20 carbon atoms, particularly preferably 6-12 carbon atoms, for example phenyl Carboxymethyl, 1-naphthyloxy, 2-naphthyloxy, 2,4,6-trimethylphenyl oxy, and 4-biphenyloxy and the like.),

Heteroaryloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include pyridyloxy, pyrazyloxy, pyrimidyloxy, and quinolyloxy. ), An alkylthio ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), arylthio ligands (Preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio), heteroarylthio ligand (preferably 1 carbon atom) To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridylthio , 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio, etc.), a siloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 3 to 25 carbon atoms). Particularly preferably, it has 6 to 20 carbon atoms, and examples thereof include a triphenylsiloxy group, a triethoxysiloxy group, and a triisopropylsiloxy group.), An aromatic hydrocarbon anion ligand (preferably having 6 carbon atoms) To 30, more preferably 6 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms, such as a phenyl anion, a naphthyl anion, an anthranyl anion, etc.), an aromatic heterocyclic anion ligand (preferably Has 1 to 30 carbon atoms, more preferably 2 to 25 carbon atoms, and particularly preferably 2 to 20 carbon atoms. Pyrrole anion, pyrazole anion, pyrazole anion, triazole anion, oxazole anion, benzoxazole anion, thiazole anion, benzothiazole anion, thiophene anion, benzothiophene anion, etc.), indolenine anion ligand, etc. Preferably a nitrogen-containing heterocyclic ligand, an aryloxy ligand, a heteroaryloxy group, an aromatic hydrocarbon anion ligand, an aromatic heterocyclic anion ligand, or a siloxy ligand, more preferably Is a nitrogen-containing heterocyclic ligand, aryloxy ligand, siloxy ligand, aromatic hydrocarbon anion ligand, or aromatic heterocyclic anion ligand.

  Examples of the metal complex electron transporting host material include, for example, Japanese Patent Application Laid-Open No. 2002-235076, Japanese Patent Application Laid-Open No. 2004-214179, Japanese Patent Application Laid-Open No. 2004-221062, Japanese Patent Application Laid-Open No. 2004-221068, Japanese Patent Application Laid-Open No. 2004-327313, And the compounds described.

  Specific examples of such an electron transporting host material include, but are not limited to, the following materials.

  The electron transport layer host material is preferably E-1 to E-6, E-8, E-9, E-10, E-21, or E-22, and E-3, E-4, E-6. E-8, E-9, E-10, E-21, or E-22 are more preferred, and E-3, E-4, E-8, E-9, E-21, or E-22 are preferred. Further preferred.

  In the light emitting layer of the present invention, when a phosphorescent dopant is used as the luminescent dopant, the lowest triplet excitation energy T1 (D) of the phosphorescent dopant and the lowest excited triplet energy of the plurality of host compounds. It is preferable in terms of color purity, external quantum efficiency, and driving durability that the above T1 (H) min satisfies the relationship of T1 (H) min> T1 (D).

(Hole-transporting host material)
The hole transporting host material used in the light emitting layer of the present invention preferably has an ionization potential Ip of 5.1 eV or more and 6.4 eV or less from the viewpoint of improving durability and lowering driving voltage. It is more preferably 6.2 eV or less, and further preferably 5.6 eV or more and 6.0 eV or less. Further, from the viewpoint of improving durability and lowering driving voltage, the electron affinity Ea is preferably 1.2 eV or more and 3.1 eV or less, more preferably 1.4 eV or more and 3.0 eV or less, and 1.8 eV or more. More preferably, it is 2.8 eV or less.

Specific examples of such a hole transporting host material include the following materials.
Pyrrole, indole, carbazole, azaindole, azacarbazole, pyrazole, imidazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic tertiary Amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, conductive polymer oligomers such as polythiophene, organic silanes, Examples thereof include carbon films and derivatives thereof.
Among them, indole derivatives, carbazole derivatives, azaindole derivatives, azacarbazole derivatives, aromatic tertiary amine compounds, and thiophene derivatives are preferable, and indole skeleton, carbazole skeleton, azaindole skeleton, azacarbazole skeleton and / or aromatic are particularly preferable in the molecule. Those having a plurality of group III tertiary amine skeletons are preferred.
Specific examples of such a hole transporting host material include, but are not limited to, the following compounds.

<Mixing ratio of luminescent material and host material>
-Mixing ratio of hole-transporting host material and electron-transporting light-emitting material The mixing ratio of hole-transporting host material and electron-transporting light-emitting material in the present invention is such that associated light emission and concentration quenching are obtained while obtaining sufficient light emission intensity. From the viewpoint of suppressing leakage of holes from the light emitting layer, the total amount of the light emitting layer is preferably 95: 5 to 50:50, more preferably 90:10 to 70:30.
-Mixing ratio of electron transporting host material and hole transporting light emitting material-
In the present invention, the mixing ratio of the electron transporting host material and the hole transporting light-emitting material is associative light emission or concentration quenching while obtaining a sufficient light emission intensity, from the viewpoint of suppressing leakage of holes from the light emitting layer, The total amount of the light emitting layers is preferably 5:95 to 50:50, more preferably 10:90 to 30:70 in terms of mass ratio.

3. Next, the configuration of the organic EL element of the present invention will be described in detail.
The organic EL device of the present invention has a cathode and an anode on a substrate, a plurality of organic compound layers including a light emitting layer between both electrodes, and an organic compound layer adjacent to both sides of the light emitting layer. Is done. An organic compound layer may be further provided between the organic compound layer adjacent to the light emitting layer and the electrode. In view of the properties of the light emitting element, at least one of the anode and the cathode is preferably transparent. Usually, the anode is transparent.

  As an aspect of lamination of the organic compound layer in the present invention, an aspect in which a hole transport layer, a light emitting layer, and an electron transport layer are laminated in this order from the anode side is preferable. Further, a charge blocking layer or the like may be provided between the hole transport layer and the light-emitting layer, or between the light-emitting layer and the electron transport layer.

  A preferred embodiment of the organic compound layer in the organic electroluminescence device of the present invention is, in order from the anode side, at least a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. It is the aspect which has.

  When the hole blocking layer is provided between the light emitting layer and the electron transporting layer, the organic compound layer adjacent to the light emitting layer is the hole transporting layer on the anode side and the hole blocking layer on the cathode side. . Further, a hole injection layer may be provided between the anode and the hole transport layer, and an electron injection layer may be provided between the cathode and the electron transport layer. Each layer may be divided into a plurality of secondary layers.

<Board>
The substrate used in the present invention is preferably a substrate that does not scatter or attenuate light emitted from the light emitting layer. Specific examples include zirconia-stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, and polycycloolefin. , Norbornene resins, and organic materials such as poly (chlorotrifluoroethylene).
For example, when glass is used as the substrate, alkali-free glass is preferably used as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what applied barrier coats, such as a silica. In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The substrate structure may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the organic light emitting layer.

The substrate can be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.
When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

<Anode>
The anode usually has a function as an electrode for supplying holes to the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. , Can be appropriately selected from known electrode materials. As described above, the anode is usually provided as a transparent anode.

  Suitable examples of the material for the anode include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. Specific examples of the anode material include conductive metals such as tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Metals such as oxides, gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Organic conductive materials, and a laminate of these and ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  The anode is composed of, for example, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as a CVD and a plasma CVD method. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material to be processed. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  In the organic electroluminescent element of the present invention, the formation position of the anode is not particularly limited and can be appropriately selected according to the use and purpose of the light emitting element. Is preferably formed on the substrate. In this case, the anode may be formed on the entire one surface of the substrate, or may be formed on a part thereof.

  The patterning for forming the anode may be performed by chemical etching such as photolithography, or may be performed by physical etching such as laser, or vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

  The thickness of the anode can be appropriately selected depending on the material constituting the anode and cannot be generally defined, but is usually about 10 nm to 50 μm, and preferably 50 nm to 20 μm.

The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less. When the anode is transparent, it may be colorless and transparent or colored and transparent. In order to take out light emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

  Note that the transparent anode is described in detail in Yutaka Sawada's “New Development of Transparent Electrode Film” published by CMC (1999), and the matters described here can be applied to the present invention. In the case of using a plastic substrate having low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

<Cathode>
The cathode usually has a function as an electrode for injecting electrons into the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element, It can select suitably from well-known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium and ytterbium. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.

Among these, as a material constituting the cathode, an alkali metal or an alkaline earth metal is preferable from the viewpoint of electron injecting property, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  The cathode materials are described in detail in JP-A-2-15595 and JP-A-5-121172, and the materials described in these publications can also be applied in the present invention.

  There is no restriction | limiting in particular about the formation method of a cathode, According to a well-known method, it can carry out. For example, the cathode described above is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the cathode material, one or more of them can be simultaneously or sequentially performed according to a sputtering method or the like.

  Patterning when forming the cathode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or by vacuum deposition or sputtering with the mask overlaid. It may be performed by a lift-off method or a printing method.

In the present invention, the cathode formation position is not particularly limited, and may be formed on the entire organic compound layer or a part thereof.
Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the cathode and the organic compound layer with a thickness of 0.1 nm to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the cathode can be appropriately selected depending on the material constituting the cathode and cannot be generally defined, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm.
Further, the cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 nm to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

<Organic compound layer>
The organic compound layer in the present invention will be described.
The organic EL device of the present invention has at least one organic compound layer including a light emitting layer, and other organic compound layers other than the light emitting layer include a hole transport layer, an electron transport layer, a charge blocking layer, a positive block layer, and the like. Examples thereof include a hole injection layer and an electron injection layer.
As described above, one of the aspects in the present invention has an interface thin layer containing a compound represented by the general formula (1) adjacent to the light emitting layer. When the interface thin layer provided on the side facing the anode contains the compound represented by the general formula (1), the interface thin layer is a hole transport layer or a layer between the hole transport layer and the light emitting layer. It is. When the compound represented by the general formula (1) is contained in the interface thin layer provided on the side facing the cathode, the interface thin layer is an electron transport layer or a layer between the electron transport layer and the light emitting layer. .

-Formation of organic compound layer-
In the organic electroluminescent element of the present invention, each layer constituting the organic compound layer is suitably formed by any of dry film forming methods such as vapor deposition and sputtering, wet coating methods, transfer methods, printing methods, and ink jet methods. be able to.

-Hole injection layer, hole transport layer-
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side. The material that can be used for the hole injection layer and the hole transport layer of the present invention is not particularly limited, and may be a low molecular compound or a high molecular compound.
Specifically, pyrrole derivatives, carbazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives , Silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organic silane derivatives, carbon, phenylazole, phenylazine A layer containing a metal complex or the like is preferable.

  An electron-accepting dopant can be contained in the hole injection layer or the hole transport layer of the organic EL device of the present invention. As the electron-accepting dopant introduced into the hole-injecting layer or the hole-transporting layer, an inorganic compound or an organic compound can be used as long as it has an electron-accepting property and oxidizes an organic compound.

  Specifically, examples of the inorganic compound include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, metal oxides such as vanadium pentoxide, and molybdenum trioxide.

In the case of an organic compound, a compound having a nitro group, halogen, cyano group, trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride compound, fullerene, or the like can be preferably used.
In addition, JP-A-6-212153, JP-A-11-111463, JP-A-11-251067, JP-A-2000-196140, JP-A-2000-286054, JP-A-2000-315580, JP-A-2001-102175, JP-A-2001-2001. -160493, JP2002-252085, JP2002-56985, JP2003-157981, JP2003-217862, JP2003-229278, JP2004-342614, JP2005-72012, JP20051666667 The compounds described in JP-A-2005-209643 and the like can be preferably used.

  These electron-accepting dopants may be used alone or in combination of two or more. Although the usage-amount of an electron-accepting dopant changes with kinds of material, it is preferable that it is 0.01 mass%-50 mass% with respect to hole transport layer material, and it is 0.05 mass%-20 mass%. It is further more preferable and it is especially preferable that it is 0.1 mass%-10 mass%.

The thicknesses of the hole injection layer and the hole transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 300 nm, and still more preferably 10 nm to 200 nm. In addition, the thickness of the hole injection layer is preferably 0.1 nm to 500 nm, more preferably 0.5 nm to 300 nm, and still more preferably 1 nm to 200 nm.
The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

-Electron injection layer, electron transport layer-
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side. The material that can be used for the electron injection layer and the electron transport layer of the present invention is not particularly limited, and may be a low molecular compound or a high molecular compound.
Specifically, pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phthalazine derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, naphthalene, perylene and other aromatic ring tetracarboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, Metal phthalocyanines, various metal complexes represented by metal complexes with benzoxazole and benzothiazole as ligands, organosilane derivatives represented by siloles Body, or the like is preferably a layer containing.

The electron injection layer or the electron transport layer of the organic EL device of the present invention can contain an electron donating dopant. The electron donating dopant introduced into the electron injecting layer or the electron transporting layer only needs to have an electron donating property and a property of reducing an organic compound, such as an alkali metal such as Li or an alkaline earth metal such as Mg. Transition metals including rare earth metals and reducing organic compounds are preferably used. As the metal, a metal having a work function of 4.2 eV or less can be preferably used. Specifically, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd , And Yb. Examples of the reducing organic compound include nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds.
In addition, materials described in JP-A-6-212153, JP-A-2000-196140, JP-A-2003-68468, JP-A-2003-229278, JP-A-2004-342614, and the like can be used.

  These electron donating dopants may be used alone or in combination of two or more. The amount of the electron-donating dopant used varies depending on the type of material, but is preferably 0.1% by mass to 30% by mass, and 0.1% by mass to 20% by mass with respect to the electron transport layer material. Is more preferable, and 0.1% by mass to 10% by mass is particularly preferable.

The thicknesses of the electron injection layer and the electron transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the electron transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the electron injection layer is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

-Hall block layer-
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing to the cathode side. In the present invention, a hole blocking layer can be provided as an organic compound layer adjacent to the light emitting layer on the cathode side.
Examples of the compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like.
The thickness of the hole blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm.
The hole block layer may have a single-layer structure made of one or more of the materials described above, or may have a multilayer structure made up of a plurality of layers having the same composition or different compositions.

-Electronic block layer-
The electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing through to the anode side. In the present invention, an electron blocking layer can be provided as the organic compound layer adjacent to the light emitting layer on the anode side.
As examples of the compound constituting the electron blocking layer, for example, those mentioned as the hole transport material described above can be applied.
The thickness of the electron blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to 100 nm.
The hole block layer may have a single-layer structure made of one or more of the materials described above, or may have a multilayer structure made up of a plurality of layers having the same composition or different compositions.

<Protective layer>
In the present invention, the entire organic EL element may be protected by a protective layer.
As a material contained in the protective layer, any material may be used as long as it has a function of preventing materials that promote device deterioration such as moisture and oxygen from entering the device.
Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ , TiO ₂ , metal nitrides such as SiN _x , SiN _x O _y , metal fluorides such as MgF ₂ , LiF, AlF ₃ , CaF ₂ , polyethylene, polypropylene, polymethyl Monomer mixture containing methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene and at least one comonomer Copolymer obtained by copolymerization, cyclic in the copolymer main chain Examples thereof include a fluorine-containing copolymer having a structure, a water-absorbing substance having a water absorption of 1% or more, and a moisture-proof substance having a water absorption of 0.1% or less.

  The method for forming the protective layer is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

<Sealing>
Furthermore, the organic electroluminescent element of this invention may seal the whole element using a sealing container.
Further, a moisture absorbent or an inert liquid may be sealed in a space between the sealing container and the light emitting element. Although it does not specifically limit as a moisture absorber, For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride Cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide, and the like. The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorinated solvents, and silicone oils. Can be mentioned.

<Drive>
The organic electroluminescence device of the present invention emits light by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Obtainable.
The driving method of the organic electroluminescence device of the present invention is described in JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234658, and JP-A-8-2441047. The driving method described in each publication, Japanese Patent No. 2784615, US Pat. Nos. 5,828,429, 6023308, and the like can be applied.

  The light-emitting element of the present invention can improve the light extraction efficiency by various known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.

  The light-emitting element of the present invention may be a so-called top emission type in which light emission is extracted from the anode side.

(Use of the present invention)
The organic electroluminescence device of the present invention can be suitably used for display devices, displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

  The present invention will be specifically described using examples, but the present invention is not limited to these examples.

Example 1
<Production of organic EL element>
(Production of Comparative Organic EL Element A)
1) Formation of anode An indium tin oxide film (hereinafter abbreviated as ITO) is deposited on a 25 mm × 25 mm × 0.7 mm glass substrate to a thickness of 100 nm (Tokyo Sanyo Vacuum Co., Ltd.). A transparent support substrate was used. This transparent support substrate was etched and washed.
2) Hole injection / transport layer

Hole injection layer: 4,4 ′, 4 ″ -tris (2-naphthylphenylamino) triphenylamine (abbreviated as 2-TNATA) and 2,3,5,6-tetrafluoro-7,7,8, 8-tetracyanoquinodimethane (abbreviated as F4-TCNQ) was co-deposited so that F4-TCNQ was 1.0 mass% with respect to 2-TNATA, and the thickness was 160 nm.
Hole transport layer: N, N′-dinaphthyl-N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (abbreviated as α-NPD), thickness 10 nm.

3) Light-emitting layer Light-emitting layer (I): hole transporting host material N, N′-dicarbazolyl-1,3-benzene (abbreviated as mCP) and polyvalent metal complex Pt-1 were co-deposited. The vapor deposition rate of each component was adjusted so that the mixing ratio of mCP and Pt-1 was 85 mass: 15 mass%. The film thickness of the light emitting layer was 67 nm.

4) Electron transport layer and electron injection layer Subsequently, the following electron transport layer and electron injection layer were provided on the light emitting layer.
Electron transport layer: Aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenolate (abbreviated as BAlq) was deposited to a thickness of 39 nm.
Electron injection layer: Bathocuproine (abbreviated as BCP) was deposited to a thickness of 1 nm.

5) Formation of cathode Further, LiF was deposited to a thickness of 1 nm, and then patterned by a shadow mask to provide Al having a thickness of 100 nm as a cathode. Each layer was provided by resistance heating vacuum deposition.

  The produced laminate was put in a glove box substituted with nitrogen gas, and sealed with a glass sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by CHI Nagase).

(Preparation of organic EL elements 1 to 3 of the present invention)
In the production of the comparative organic EL element A, the light emitting layer was divided and the divided light emitting layer, the interface thin layer and the intermediate thin layer described below were used, and the production of the present invention was performed in exactly the same manner as in the production of the comparative organic EL element A. Organic EL elements 1 to 3 were produced.
Separate light emitting layer: Only the vapor deposition thickness was changed with the same composition as the light emitting layer of the comparative organic EL element A.
Composition of interfacial thin layer and intermediate thin layer: Compound AD1 of general formula (1) was deposited in the thickness shown in Table 1.

The arrangement order in the light emitting layer is shown below in the order from the hole transport layer side.
Element 1: Interface thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / Intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / interface Thin layer (0.5nm)
The total thickness was 63.5 nm.
Element 2: Same as Element 1, except that the deposition thickness of the interface thin layer and the intermediate thin layer was changed to 1.0 nm. The total thickness was 67 nm.
Element 3: Same as Element 1, except that the deposition thickness of the interface thin layer and the intermediate thin layer was changed to 2.0 nm. The total thickness was 74 nm.

(Production of organic EL elements 4 to 6 of the present invention)
Element 4: Interface thin layer (0.5 nm) / divided light emitting layer (20 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (20 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (20 nm) / Interface thin layer (0.5nm)
The total thickness was 62 nm.
Element 5: Same as Element 4, except that the deposition thickness of the interface thin layer and the intermediate thin layer was changed to 1.0 nm. The total thickness was 64 nm.
Element 6: Same as Element 4, except that the deposition thickness of the interface thin layer and the intermediate thin layer was changed to 2.0 nm. The total thickness was 68 nm.

(Production of organic EL elements 7 to 9 of the present invention)
Element 7: Split light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / split light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / split light emitting layer (10 nm) / intermediate thin layer (0.5 nm) ) / Divided luminescent layer (10 nm) / intermediate thin layer (0.5 nm) / divided luminescent layer (10 nm) / intermediate thin layer (0.5 nm) / divided luminescent layer (10 nm) / interface thin layer (0.5 nm)
The total thickness was 63 nm.
Element 8: interface thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / Intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm)
The total thickness was 63 nm.
Element 9: divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / Divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm)
The total thickness was 62.5 nm.

<Performance evaluation of organic EL elements>
1) External quantum efficiency Using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd., a direct current voltage was applied to each element to emit light. The brightness was measured using a luminance meter BM-8 manufactured by Topcon Corporation. The emission spectrum and emission wavelength were measured using a spectrum analyzer PMA-11 manufactured by Hamamatsu Photonics. Based on these numerical values, the external quantum efficiency at a luminance of 360 cd / m ² was calculated by a luminance conversion method.

2) Driving voltage Using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd., a DC voltage was applied to each element to emit light. The voltage when the current value flowing through the element was 10 mA / cm ² was measured as the drive voltage.
3) driving durability: a luminance half-life each element by applying a DC voltage so that the luminance 360 cd / ^{m 2,} the luminance was measured the time until 180 cd / ^{m 2} is continuously driven. This luminance half time was used as an index of driving durability.

  The results obtained are summarized in Table 1 below.

  As is clear from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability with respect to the comparative device A. In particular, among the elements 1 to 3 of the present invention, the thinnest element 1 showed the best performance with the deposition thickness of the interface thin layer and the intermediate thin layer being 0.5 nm. Among the elements 4 to 6 of the present invention, the thinnest element 4 showed the best performance, with the deposition thickness of the interface thin layer and the intermediate thin layer being 0.5 nm. In addition, among the elements 7 to 9 of the present invention, the element 8 in which the thickness of the divided light emitting layer was as thin as 10 nm and the interface thin layer was provided in the anode side interface region showed the most excellent performance.

Example 2
1. Preparation of Sample Organic EL element 1 of Example 1 except that the constituent material AD1 of the interface thin layer and the intermediate thin layer was changed to AD2 in the preparation of organic EL elements 1, 4, 7, 8, and 9 of Example 1. , 4, 7, 8, and 9 were produced in the same manner as in the organic EL elements 10 to 14 of the present invention.

2. Performance Evaluation The results evaluated in the same manner as in Example 1 are shown in Table 2.

  As is clear from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability compared to the device A of Comparative Example 1 of the present invention. Had. In particular, among the elements 10 to 14 of the present invention, the element 10 in which the thickness of the divided light emitting layer is as thin as 10 nm and the interface thin layer is provided in both the anode side and cathode side interface regions showed the most excellent performance.

Example 3
1. Preparation of Sample In the preparation of the organic EL elements 10 to 14 of Example 2, exactly the same as the preparation of the organic EL elements 10 to 14 of Example 2, except that the constituent material AD2 of the interface thin layer and the intermediate thin layer was changed to AD3. Thus, organic EL elements 15 to 19 of the present invention were produced.

2. Performance Evaluation The results evaluated in the same manner as in Example 1 are shown in Table 3.

  As is clear from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability compared to the device A of Comparative Example 1 of the present invention. Had. In particular, among the elements 15 to 19 of the present invention, the element 15 provided with an interface thin layer in both the anode side and cathode side interface regions showed the most excellent performance.

Example 4
1. Preparation of Sample In the preparation of the organic EL elements 10 to 14 of Example 2, the same as the preparation of the organic EL elements 10 to 14 of Example 2, except that the constituent material AD2 of the interface thin layer and the intermediate thin layer was changed to AD4. Thus, organic EL elements 20 to 24 of the present invention were produced.

2. Performance Evaluation The results evaluated in the same manner as in Example 1 are shown in Table 4.

  As is clear from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability compared to the device A of Comparative Example 1 of the present invention. Had. In particular, among the devices 20 to 24 of the present invention, the device 20 in which the thickness of the divided light emitting layer was as thin as 10 nm and the interface thin layer was provided in both the anode side and cathode side interface regions showed the most excellent performance.

Example 5
1. Preparation of Sample In the preparation of the organic EL element of Example 1, the comparative organic EL element B and the present invention were exactly the same as the preparation of the organic EL element of Example 1 except that the light emitting material Pt-1 was changed to Pt-2. Inventive organic EL elements 25 to 33 were prepared.

2. Performance Evaluation The results evaluated in the same manner as in Example 1 are shown in Table 5.

  The results obtained are summarized in Table 5 below.

  As is clear from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability with respect to the comparative device B. In particular, among the elements 25 to 27 of the present invention, the element 25 having the thinnest layer showed the best performance with the deposition thickness of the interface thin layer and the intermediate thin layer being 0.5 nm. Among the elements 28 to 30 of the present invention, the thinnest element 28 showed the best performance, with the deposition thickness of the interface thin layer and the intermediate thin layer being 0.5 nm. Among the elements 31 to 33 of the present invention, the element 32 provided with the interface thin layer in the anode side interface region showed the most excellent performance.

Example 6
1. Preparation of Sample Organic EL elements 25 and 28 of Example 1 except that in the preparation of organic EL elements 25 and 28 and 31 to 33 of Example 5, the constituent material AD1 of the interface thin layer and the intermediate thin layer was changed to AD2. The organic EL elements 34 to 38 of the present invention were produced in exactly the same manner as the production of 31 and 33.

2. Performance Evaluation The results evaluated in the same manner as in Example 1 are shown in Table 6.

  As is apparent from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability compared to the comparative device B of Example 5 of the present invention. Had. In particular, among the elements 34 to 38 of the present invention, the element 34 in which the thickness of the divided light emitting layer was as thin as 10 nm and the interface thin layer was provided in both the anode side and cathode side interface regions showed the most excellent performance.

Example 7
1. Sample Preparation In the manufacture of the organic EL elements 34 to 38 of Example 6, the same procedure as that of the organic EL elements 34 to 38 of Example 6 was performed except that the constituent material of the interface thin layer and the intermediate thin layer was changed to AD3. Thus, organic EL elements 39 to 43 of the present invention were produced.

2. Performance Evaluation The results evaluated in the same manner as in Example 1 are shown in Table 7.

  As is apparent from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability compared to the comparative device B of Example 5 of the present invention. Had. In particular, among the elements 39 to 43 of the present invention, the element 39 in which the thickness of the divided light emitting layer was as thin as 10 nm and the interface thin layer was provided in both the anode side and cathode side interface regions showed the most excellent performance.

Example 8
1. Sample Preparation In the manufacture of the organic EL elements 34 to 38 in Example 6, the same procedure as in the preparation of the organic EL elements 34 to 38 in Example 6 was performed except that the constituent materials of the interface thin layer and the intermediate thin layer were changed to AD4. Thus, organic EL elements 44 to 48 of the present invention were produced.

2. Performance Evaluation The results evaluated in the same manner as in Example 1 are shown in Table 8.

  As is apparent from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability compared to the comparative device B of Example 5 of the present invention. Had. In particular, among the elements 44 to 48 of the present invention, the element 44 in which the thickness of the divided light emitting layer was as thin as 10 nm and the interface thin layer was provided in both the anode side and cathode side interface regions showed the most excellent performance.

Example 9
1. Preparation of Sample In the preparation of the organic EL element of Example 1, the comparison and the organic EL elements 49 to 52 of the present invention were made in exactly the same manner as the preparation of the organic EL element of Example 1 except that the light emitting layer was changed to the following layer. Was made.

(Comparison organic EL element C)
Light-emitting layer (c): host material N, N′-di-carbazolyl-4,4′-biphenyl (abbreviated as CBP) and light-emitting material fac-tris (2-phenylpyridinate-N, C2 ′) Iridium (III) ( Ir _{(ppy) 3} Ir the abbreviated) against CBP and _{(ppy) 3} were co-deposited to a 5 mass%. The thickness of the light emitting layer was 30 nm.

(Comparison organic EL element D)
Light-emitting layer (d): host material BAlq and light-emitting material tris (1-phenylisoquinolinate) Iridium (III) (abbreviated as Ir (piq) ₃ ) so that Ir (piq) ₃ is 5% by mass with respect to BAlq. Co-deposited. The thickness of the light emitting layer was 30 nm.

(Comparison organic EL element E)
Light emitting layer (e): Compound AD1 of general formula (1) and light emitting material Ir (piq) ₃ were co-deposited so that Ir (piq) ₃ was 7% by mass with respect to compound AD1 of general formula (1). . The thickness of the light emitting layer was 30 nm.

(Preparation of the organic EL element 49 of the present invention)
In the production of the comparative organic EL element C, the light emitting layer was divided, and the divided light emitting layer, the interface thin layer and the intermediate thin layer described below were used, and exactly the same as the production of the comparative organic EL element C. An organic EL element 49 was produced.
Divided light emitting layer: Only the deposition thickness was changed with the same composition as the light emitting layer of the comparative organic EL device C.
Composition of interfacial thin layer and intermediate thin layer: Compound AD1 represented by the general formula (1) was vapor-deposited with the thickness shown in Table 9.

The arrangement order in the light emitting layer is shown below in the order from the hole transport layer side.
Element 49: interface thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / Intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / interface Thin layer (0.5nm)
The total thickness was 63.5 nm.

(Preparation of the organic EL device 50 of the present invention)
In the production of the comparative organic EL element D, the light emitting layer was divided, and the divided light emitting layer, the interface thin layer and the intermediate thin layer described below were used, and exactly the same as the production of the comparative organic EL element D of the present invention. An organic EL element 50 was produced.
Divided light emitting layer: Only the vapor deposition thickness was changed with the same composition as the light emitting layer of the comparative organic EL device D.
Composition of interfacial thin layer and intermediate thin layer: Compound AD1 represented by the general formula (1) was vapor-deposited with the thickness shown in Table 9.

The arrangement order in the light emitting layer is shown below in the order from the hole transport layer side.
Element 50: interface thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / Intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / interface Thin layer (0.5nm)
The total thickness was 63.5 nm.

2. Performance Evaluation The performance of the obtained device was evaluated in the same manner as in Example 1. The results are shown in Table 9.
As a result, as is clear from the above results, the device 49 of the present invention with respect to the comparative device C and the device 50 of the present invention with respect to the comparative device D have unexpectedly high external quantum efficiency and low driving voltage, respectively. And high driving durability. The comparative device E using the compound AD1 of the general formula (1) in the light emitting layer did not emit light.

Example 10
1. Preparation of organic EL element (production of comparative organic EL element F)
1) Formation of anode An indium tin oxide film (hereinafter abbreviated as ITO) is deposited on a 25 mm × 25 mm × 0.7 mm glass substrate to a thickness of 100 nm (Tokyo Sanyo Vacuum Co., Ltd.). A transparent support substrate was used. This transparent support substrate was etched and washed.
2) Hole injection layer, hole transport layer

Hole injection layer: 2-TNATA and F4-TCNQ were co-deposited so that F4-TCNQ was 1.0 mass% with respect to 2-TNATA. The thickness was 160 nm.
Hole transport layer: α-NPD was deposited to a thickness of 10 nm.

3) Light emitting layer Light emitting layer (I): hole transporting host material H-1 and polyvalent metal complex Pt-3 were co-evaporated. The vapor deposition rate of each component was adjusted so that the mixing ratio of H-1 and Pt-3 was 85 mass: 15 mass%. The thickness of the light emitting layer was 30 nm.

4) Electron transport layer and electron injection layer Subsequently, the following electron transport layer and electron injection layer were provided on the light emitting layer.
Electron transport layer: BAlq was deposited to a thickness of 39 nm.
Electron injection layer: BCP was deposited to a thickness of 1 nm.

  Furthermore, after depositing LiF to a thickness of 1 nm, patterning was performed using a shadow mask to provide Al having a thickness of 100 nm as a cathode. Each layer was provided by resistance heating vacuum deposition.

  The produced laminate was put in a glove box substituted with nitrogen gas, and sealed with a glass sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by CHI Nagase).

(Preparation of the organic EL elements 51 to 53 of the present invention)
In the production of the comparative organic EL element F, the light emitting layer was divided and the divided light emitting layer, the interface thin layer and the intermediate thin layer described below were used, and exactly the same as the production of the comparative organic EL element F of the present invention. Organic EL elements 51 to 53 were produced.
Split light emitting layer: Only the vapor deposition thickness was changed with the same composition as the light emitting layer of the comparative organic EL element F.
Composition of interfacial thin layer and intermediate thin layer: Compound AD5 of the general formula (1) was deposited in the thickness shown in Table 10.

The arrangement order in the light emitting layer is shown below in the order from the hole transport layer side.
Element 51: interface thin layer (0.5 nm) / divided light emitting layer (10 nn) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nn) / intermediate thin layer (0.5 nm) / divided light emitting layer (10nn) Interfacial thin layer (0.5 nm)
The total thickness was 32 nm.
Element 52: The same as Element 1, except that the vapor deposition thickness of the interface thin layer and the intermediate thin layer was changed to 1.0 nm. The total thickness was 34 nm.
Element 53: Same as Element 1, except that the vapor deposition thickness of the interface thin layer and the intermediate thin layer was changed to 2.0 nm. The total thickness was 38 nm.

(Preparation of organic EL elements 54 to 55 of the present invention)
Element 54: divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / interface thin layer (0.5 nm)
The total thickness was 31.5 nm.
Element 55: interface thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm) / intermediate thin layer (0.5 nm) / divided light emitting layer (10 nm)
The total thickness was 31.5 nm.

2. Performance Evaluation 1) External Quantum Efficiency Using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd., a direct current voltage was applied to each element to emit light. The brightness was measured using a luminance meter BM-8 manufactured by Topcon Corporation. The emission spectrum and emission wavelength were measured using a spectrum analyzer PMA-11 manufactured by Hamamatsu Photonics. Based on these numerical values, the external quantum efficiency at a luminance of 360 cd / m ² was calculated by a luminance conversion method.

2) Driving voltage Using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd., a DC voltage was applied to each element to emit light. The voltage when the current value flowing through the element was 10 mA / cm ² was measured as the drive voltage.
3) driving durability: a luminance half-life each element by applying a DC voltage so that the luminance 360 cd / ^{m 2,} the luminance was measured the time until 180 cd / ^{m 2} is continuously driven. This luminance half time was used as an index of driving durability.

  The results obtained are summarized in Table 10 below.

  As is clear from the above results, the device of the present invention had unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability with respect to the comparative device F. In particular, among the elements 51 to 53 of the present invention, the thinnest element 51 showed the best performance with the deposition thickness of the interface thin layer and the intermediate thin layer being 0.5 nm. In addition, among the elements 54 to 55 of the present invention, the element 55 provided with the interface thin layer in the anode side interface region showed the most excellent performance.

Example 11
(Production of Comparative Organic EL Element G)

A comparative device F in Example 10 was prepared in the same manner as the comparative device F except that the light emitting layer was changed as follows.
Light emitting layer: A hole transporting host material H-2 and a polyvalent metal complex Pt-3 were co-evaporated. The vapor deposition rate of each component was adjusted so that the mixing ratio of H-2 and Pt-3 was 85 mass: 15 mass%. The thickness of the light emitting layer was 30 nm.

(Production of organic EL elements 56 to 60 of the present invention)
In the production of the organic EL elements 51 to 55 of the present invention, the organic EL elements 56 to 55 of the present invention were exactly the same as the elements 51 to 55 of the present invention, except that the divided light emitting layer was changed to the composition of the comparative element G. 60 was produced.

  The results obtained are summarized in Table 11 below.

  As is clear from the above results, the device of the present invention has unexpectedly high external quantum efficiency, light emission characteristics at a low driving voltage, and high driving durability with respect to the comparative device G. In particular, among the elements 56 to 58 of the present invention, the thinnest element 56 showed the most excellent performance with the deposition thickness of the interface thin layer and the intermediate thin layer being 0.5 nm. In addition, among the elements 59 to 60 of the present invention, the element 60 provided with the interface thin layer in the anode side interface region showed the most excellent performance.

It is a cross-sectional schematic diagram which shows the structure of the light emitting layer of the conventional organic EL element, and its adjacent layer. It is a cross-sectional schematic diagram which shows the structure of the light emitting layer of the organic EL element of this application, and its adjacent layer. It is a cross-sectional schematic diagram which shows the structure of the light emitting layer of the organic EL element of another aspect of this application, and its adjacent layer. It is a cross-sectional schematic diagram which shows the structure of the light emitting layer of the organic EL element of another aspect of this application, and its adjacent layer.

Claims (16)

An organic electroluminescence device comprising at least one organic compound layer including a light emitting layer between a pair of electrodes, wherein at least one of the inside of the light emitting layer and the region of the light emitting layer facing the adjacent layer of the light emitting layer An organic electroluminescent device comprising a layer containing a compound represented by the following general formula (1):

(In General Formula (1), R _{1 to} R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or aryl. Group, heteroaryl group, alkoxy group having 1 to 6 carbon atoms, acyl group, acyloxy group, amino group, nitro group, cyano group, ester group, amide group, halogen atom, perfluoroalkyl group having 1 to 6 carbon atoms, Represents a silyl group, and at least one of R _{1 to} R ₄ is a group having a double bond or a triple bond, X _{1 to} X ₁₂ each independently represents a hydrogen atom, an alkyl having 1 to 6 carbon atoms; Group, alkenyl group having 2 to 6 carbon atoms, alkynyl group having 2 to 6 carbon atoms, aryl group, heteroaryl group, alkoxy group having 1 to 6 carbon atoms, acyl group, acyloxy group, amino group, nitro group, cyano group , D Ether group, an amide group, a halogen atom, a perfluoroalkyl group having 1 to 6 carbon atoms, a silyl group.).   2. The organic electroluminescent element according to claim 1, wherein the layer containing the compound represented by the general formula (1) has a thickness of 0.1 nm or more and less than 3 nm.   The organic electroluminescent element according to claim 1 or 2, wherein the layer containing the compound represented by the general formula (1) is an intermediate thin layer inside the light emitting layer.   The layer containing the compound represented by the general formula (1) is an interface thin layer on the side facing the anode of the light-emitting layer. Organic electroluminescent element.   5. The layer according to claim 1, wherein the layer containing the compound represented by the general formula (1) is an interface thin layer on a side facing the cathode of the light emitting layer. Organic electroluminescent element.   The intermediate thin layer includes a plurality of intermediate thin layers inside the light emitting layer, and the plurality of intermediate thin layers are arranged at intervals of 5 nm or more and 20 nm or less. The organic electroluminescent element according to item.   7. The energy difference (denoted as Eg) between the highest occupied orbit and the lowest unoccupied orbit of the compound represented by the general formula (1) is 4.0 eV or more. 2. The organic electroluminescent element according to item 1. According to any one of claims 1 to 7, the lowest triplet excitation level of the compound represented by the general formula (1) (T ₁ hereinafter) is characterized in that at least 2.7eV Organic electroluminescent element. The organic electroluminescence device according to any one of claims 1 to 8, wherein the compound represented by the general formula (1) has an electron affinity (denoted as Ea) of 2.3 eV or less. . The organic electroluminescence device according to any one of claims 1 to 9, wherein an ionization potential (denoted as Ip) of the compound represented by the general formula (1) is 6.1 eV or more. .   The organic electroluminescent element according to any one of claims 1 to 10, wherein the group having a double bond is an aryl group.   The organic electroluminescent device according to claim 11, wherein the aryl group is a phenyl group.   The organic light emitting device according to claim 1, wherein the light emitting layer contains a metal complex.   The organic electroluminescent element according to claim 13, wherein the metal complex is a metal complex having a tridentate or higher ligand. The organic electroluminescent element according to claim 13 or 14, wherein the metal complex is a metal complex represented by the following general formula (A):

(In General Formula (A), M ¹¹ represents a metal ion, and L ^{11 to} L ¹⁵ each independently represents a ligand coordinated to M ^{11. An} atomic group between L ¹¹ and L ¹⁴ May be further present to form a cyclic ligand, L ¹⁵ may be bonded to both L ¹¹ and L ¹⁴ to form a cyclic ligand, and Y ¹¹ , Y ¹² and Y ¹³ are Each independently represents a linking group, a single bond, or a double bond, and when Y ¹¹ , Y ¹² , or Y ¹³ is a linking group, L ¹¹ and Y ¹² , Y ¹² and L ¹² , L ¹² And Y ¹¹ , Y ¹¹ and L ¹³ , L ¹³ and Y ¹³ , and Y ¹³ and L ¹⁴ each independently represent a single bond or a double bond, and n ¹¹ represents 0 to 4. M binding of ¹¹ and ^L 11 ^{~L 15} are each independently, coordinate bond, an ionic bond, Izu covalent bond But good.). The organic electroluminescent device of claim 15 wherein M ¹¹ in the general formula (A) is characterized in that it is a platinum ion.